230 OCEANIC BIRD LIFE 



open ocean, are afraid of the land, only coming ashore at night when they 

 have to for breeding. Moreover, they all inhabit self-made tunnels which 

 in the case of some species may be up to a couple of metres long. Unfor- 

 tunately they are very helpless on land, being incapable of defending 

 themselves against their worst enemy the rat, which enters their tunnels 

 and devours adult birds, young, and eggs. The destruction of these defence- 

 less birds by rats is said to have been disastrous to many species of petrels. 

 On Campbell Island, for example, we were told that they had been 

 almost exterminated and now bred only on islets and rocks off the coasts. 



There are few place in the world where sea-bird life is as rich and varied 

 as in the waters surrounding New Zealand. The country extends from 

 the stormy west-wind belt in the south to the calm subtropical zone in the 

 north. This climatic zonation, together with its situation in the Pacific, 

 has resulted in a varied bird life. In New Zealand waters one finds 

 breeding representatives both of subtropical and sub-antarctic birds, and 

 even migrants and stray birds from the Antarctic islands. Nowhere else 

 did we see so many birds during the day as we did off New Zealand, 

 both on the open sea and along the coasts. Standing on the bridge, there 

 was always something to see. Small petrels predominated. Nearly half 

 of the world's albatrosses and petrels breed in New Zealand and on 

 surrounding islands. These enormous numbers of birds breed in a rela- 

 tively limited area, some on capes and small islands along the coasts and 

 some on a small number of bird islands out at sea. 



North, east, and south of New Zealand are a number of scattered 

 islands in the Pacific. Most of these are uninhabited, and a few are only 

 large rocks. Others are rather larger, and overgrown with inaccessible 

 woods and hills. All these islands are well known for their bird life, and 

 some, including Campbell Island and the Kermadecs, are famous bird 

 islands. Hundreds of thousands of sea-birds inhabit them - — ■ albatrosses, 

 penguins, shearwaters. Cape pigeons, giant petrels, diving petrels, small 

 petrels, great skuas, and one species of gull. On a few of the islands live 

 land birds which are found nowhere else in the world. Most of the sea- 

 birds, especially outside the breeding season, range over a very wide sea 

 area in the southern Pacific — no one knows how far. 



Every sea region has its characteristic bird fauna like every land region, 

 though the distribution of sea-birds, both as to species and numbers, is 

 more even than that of land birds. Generally speaking, sea-birds are distri- 

 buted in a circular zone round the earth, a fact which is particularly evident 

 in the southern hemisphere. The reasons for this are the food poten- 

 tialities, and, though the birds spend most of their time in the air, it is 



